An antenna is an apparatus that has a low input/output impedance at a particular operational bandwidth(s) and has a higher input/output impedance at other frequencies. The operational bandwidth is a frequency range over which an antenna can efficiently operate. Efficient operation occurs, for example, when the antenna's input/output impedance is greater than an operational threshold.
A radio frequency antenna will easily transmit and/or receive radio waves within its operational bandwidth.
It is desirable to reduce the impact an antenna has on an electronic device that houses the antenna. In particular, at the frequencies used for radio communication a radiator element of an antenna may be large compared to the size of the device.
A planar inverted F antenna (PIFA) addresses this problem. It excites a planar conductive element (e.g. a ground plane) which then acts as the radiator of the antenna. The existing printed wiring board of the electronic device may provide the planar conductive element. However, a PIFA typically requires an additional conductive element parallel to the ground plane at either the top or bottom end of the ground plane. The requirements for the size, spacing and positioning of this additional conductive element may be problematic.
According to various, but not necessarily all, embodiments of the invention there is provided an apparatus comprising: a conductive element comprising an area of conductive material defined by a plurality of edges including at least a first edge wherein the conductive ground plane element comprises:    a first interior aperture in the area of conductive material and a first elongate portion defined by a gap at the first edge of the conductive element and by at least a portion of the interior aperture; and    a second interior aperture in the area of conductive material and a second elongate portion defined by a second gap, by at least a portion of the first interior aperture and by at least a portion of the second interior aperture.
According to various, but not necessarily all, embodiments of the invention there is provided an apparatus comprising: a conductive element comprising an elongate area of conductive material defined by a plurality of edges including at least one elongate edge wherein the conductive ground plane element comprises an interior aperture in the area of conductive material and an elongate portion defined by a gap at the elongate edge of the conductive ground plane and by at least a portion of the interior aperture; and a feed element.
According to various, but not necessarily all, embodiments of the invention there is provided an apparatus comprising: a conductive element comprising: a conductive ground plane element comprising an edge wherein the conductive ground plane element comprises an interior aperture in the conductive ground plane element and an elongate portion defined by a gap at the edge of the conductive ground plane and by at least a portion of the interior aperture; and a feed element adjacent to but separated from the elongate portion and separated from the conductive ground plane element.
According to various, but not necessarily all, embodiments of the invention there is provided an apparatus comprising: a conductive element comprising: a ground plane with an aperture adjacent an edge of the ground plane; and a feed configured to indirectly feed a closed-loop electric current path comprising portions of the ground plane adjacent the aperture to enable radio wave radiation by the ground plane.